linux-kernel - [PATCH v2] dmaengine: xgene-dma: Fix the lock to allow client for further submission of requests

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Message-Id: <1440147814-22016-1-git-send-email-rsahu@apm.com>
Date:	Fri, 21 Aug 2015 14:33:34 +0530
From:	Rameshwar Prasad Sahu <rsahu@....com>
To:	vinod.koul@...el.com, dan.j.williams@...el.com
Cc:	dmaengine@...r.kernel.org, arnd@...db.de,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, jcm@...hat.com,
	patches@....com, Rameshwar Prasad Sahu <rsahu@....com>
Subject: [PATCH v2] dmaengine: xgene-dma: Fix the lock to allow client for further submission of requests

This patch provides the fix in the cleanup routing such that client can perform
further submission by releasing the lock before calling client's callback function.

Signed-off-by: Rameshwar Prasad Sahu <rsahu@....com>
---
 drivers/dma/xgene-dma.c | 33 ++++++++++++++++++++++-----------
 1 file changed, 22 insertions(+), 11 deletions(-)

diff --git a/drivers/dma/xgene-dma.c b/drivers/dma/xgene-dma.c
index d1c8809..0b82bc0 100644
--- a/drivers/dma/xgene-dma.c
+++ b/drivers/dma/xgene-dma.c
@@ -763,12 +763,17 @@ static void xgene_dma_cleanup_descriptors(struct xgene_dma_chan *chan)
 	struct xgene_dma_ring *ring = &chan->rx_ring;
 	struct xgene_dma_desc_sw *desc_sw, *_desc_sw;
 	struct xgene_dma_desc_hw *desc_hw;
+	struct list_head ld_completed;
 	u8 status;

+	INIT_LIST_HEAD(&ld_completed);
+
+	spin_lock_bh(&chan->lock);
+
 	/* Clean already completed and acked descriptors */
 	xgene_dma_clean_completed_descriptor(chan);

-	/* Run the callback for each descriptor, in order */
+	/* Move all completed descriptors to ld completed queue, in order */
 	list_for_each_entry_safe(desc_sw, _desc_sw, &chan->ld_running, node) {
 		/* Get subsequent hw descriptor from DMA rx ring */
 		desc_hw = &ring->desc_hw[ring->head];
@@ -811,15 +816,17 @@ static void xgene_dma_cleanup_descriptors(struct xgene_dma_chan *chan)
 		/* Mark this hw descriptor as processed */
 		desc_hw->m0 = cpu_to_le64(XGENE_DMA_DESC_EMPTY_SIGNATURE);

-		xgene_dma_run_tx_complete_actions(chan, desc_sw);
-
-		xgene_dma_clean_running_descriptor(chan, desc_sw);
-
 		/*
 		 * Decrement the pending transaction count
 		 * as we have processed one
 		 */
 		chan->pending--;
+
+		/*
+		 * Delete this node from ld running queue and append it to
+		 * ld completed queue for further processing
+		 */
+		list_move_tail(&desc_sw->node, &ld_completed);
 	}

 	/*
@@ -828,6 +835,14 @@ static void xgene_dma_cleanup_descriptors(struct xgene_dma_chan *chan)
 	 * ahead and free the descriptors below.
 	 */
 	xgene_chan_xfer_ld_pending(chan);
+
+	spin_unlock_bh(&chan->lock);
+
+	/* Run the callback for each descriptor, in order */
+	list_for_each_entry_safe(desc_sw, _desc_sw, &ld_completed, node) {
+		xgene_dma_run_tx_complete_actions(chan, desc_sw);
+		xgene_dma_clean_running_descriptor(chan, desc_sw);
+	}
 }

 static int xgene_dma_alloc_chan_resources(struct dma_chan *dchan)
@@ -876,11 +891,11 @@ static void xgene_dma_free_chan_resources(struct dma_chan *dchan)
 	if (!chan->desc_pool)
 		return;

-	spin_lock_bh(&chan->lock);
-
 	/* Process all running descriptor */
 	xgene_dma_cleanup_descriptors(chan);

+	spin_lock_bh(&chan->lock);
+
 	/* Clean all link descriptor queues */
 	xgene_dma_free_desc_list(chan, &chan->ld_pending);
 	xgene_dma_free_desc_list(chan, &chan->ld_running);
@@ -1200,15 +1215,11 @@ static void xgene_dma_tasklet_cb(unsigned long data)
 {
 	struct xgene_dma_chan *chan = (struct xgene_dma_chan *)data;

-	spin_lock_bh(&chan->lock);
-
 	/* Run all cleanup for descriptors which have been completed */
 	xgene_dma_cleanup_descriptors(chan);

 	/* Re-enable DMA channel IRQ */
 	enable_irq(chan->rx_irq);
-
-	spin_unlock_bh(&chan->lock);
 }

 static irqreturn_t xgene_dma_chan_ring_isr(int irq, void *id)
--
1.8.2.1

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